Thursday, May 21, 2009

Problems in Genetic Transformation

Tissue culture has been identified as one of the largest obstacles in the development of transgenic plant products. It is necessary to develop protocols that allow the regeneration of whole individuals from the transformed cells or tissue. One of the difficulties faced by scientists is that regeneration methodologies work well with some, but not all species or germplasm within a species. This severely limits the spectrum of individuals that can be transformed. In many cases, the procedure has been the transfer of the transgene through classical genetics and breeding methods. An example of this is in the genetic transformation of wheat. Genetic transformation of most wheat varieties is very difficult because of problems in tissue culture. One variety, Bobwhite, is the exception, and protocols have been developed for the transformation of this wheat variety. Once a gene has been successfully transferred into Bobwhite, it can be moved into other varieties through traditional breeding methods.

Another difficulty associated with the use of tissue culture in transformation is somaclonal variations. Plants produced from tissue culture have higher mutation rates and the appearance of abnormal variation. This is due to the delicate environment in which cells are cultured. Many times, the cultured plants have problems associated with the cell cultures and not from the transgene integration.

Transformation methods currently in development promise to revolutionize the introduction of genes in plants. Some of these methods are already being used with the model plant Arabidopsis thaliana, commonly known as mouse ear cress. One of the methods involves the submersion of floral buds in a solution containing plasmids bearing the transgenes. Another alternative technique, still in development, is the transformation of seeds mediated by Agrobacterium tumefaciens. Although the methods have been used with success in Arabidopsis, the literature does not report its use in crop species. The key aspect of these two methods is that transformation is carried out without the need to regenerate plants through tissue culture. These methods are exciting because the transformation procedure works on the seeds that can then be planted to identify transgenic individuals.

Tags: Bio Technology, Bio Genetics, Genetic Transformation

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